A group of lichens characteristic features representatives of the table. Forms of lichens and their names. What does a lichen look like
Lichens are symbiotic associations mushrooms (mycobiont) and microscopic green algae and/or cyanobacteria (photobiont, or phycobiont); the mycobiont forms a thallus (thallus), inside which the photobiont cells are located. The fungus in this case is either marsupial or basidial, and the algae is either green or blue-green. Lichens usually settle on bare rocks or tree trunks. Algae supplies the fungus with organic products of photosynthesis, and the fungus provides water and mineral salts.
Lichens grow very slowly and are sensitive to environmental pollution, so they are an ideal indicator of atmospheric pollution, especially sulfur dioxide. Lichen thallus has different shapes, sizes and colors.
The attachment organs of lichens are rhizoids And rizina (connected in strands of rhizoids).
Diversity of lichens
Lichens are white, grey, yellow, orange, green, black ; this is determined by the nature of the pigment in the hyphal sheath. Pigmentation helps to protect against excessive light or, conversely, helps to absorb more light (the black pigment of Antarctica lichens).
According to the form and nature of attachment to the substrate, three groups lichens:
- scale forms - have the appearance of a crust or plaque, tightly adhering to the substrate (edible lecanora, graphis, lecidea);
- leafy forms - have the form of plates with dissected, branching lobes; their resemblance to the leaves is very distant (xanthoria - wall goldfish, parmelia);
- bushy lichens - upright or hanging bushes. (cladonia, reindeer moss - deer moss, cetraria - Icelandic moss, bearded man).
According to the anatomical structure, lichens are divided into homeomeric (algae scattered throughout the body of the lichen) and heteromeric (algae form a separate layer in the thallus).
Lichens with heteromeric thallus are the majority. In a heteromeric thallus, the top layer is cortical composed of fungal hyphae. It protects the thallus from drying out and mechanical influences. The next layer from the surface - gonidial, or algal, it contains a photobiont. Located in the center core, consisting of randomly intertwined hyphae of the fungus. Moisture is mainly stored in the core, it also plays the role of a skeleton. At the lower surface of the thallus is often located lower cortex, with the help of the outgrowths of which ( rizin) the lichen is attached to the substrate. A complete set of layers is not found in all lichens.
Lichen reproduction
Reproduction of lichens occurs by spores or vegetatively: fragments of the thallus (isidia and soredia). Sexual reproduction is provided by special sections of the thallus that form spores. The spore germinates into a hyphae, and upon encountering a suitable algae, a new lichen is formed.
The role of lichens in nature and human life
The role of lichens in nature hard to overestimate. They are "pioneers" in the formation of plant communities. By releasing organic acids, lichens destroy the parent rock, and when their organics die, together with it, they form the primary soil on which plants can settle. Lichens serve as food for many animals (reindeer moss or reindeer moss), are a habitat for many invertebrates.
Role in human life. Lichens serve as indicators of air pollution. Some species are used by humans for food (lichen manna). Also, lichens are used in industry (making litmus), in perfumery (obtaining aromatic substances), in the pharmaceutical industry (obtaining drugs against tuberculosis, furunculosis, epilepsy, etc.). Lichen acids also have antibiotic properties.
Table "Lichens"
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Lichens are peculiar complex organisms, the thallus of which is a combination of fungus and algae, which are in complex relationships with each other, more often in symbiosis. More than 20 thousand species of lichens are known.
From other organisms, including free-living fungi and algae, they differ in shape, structure, nature of metabolism, special lichen substances, methods of reproduction, and slow growth (from 1 to 8 mm per year).
Structural features
lichen thallus consists of intertwined fungal threads - hyphae, and algae cells (or threads) located between them.
There are two main types of microscopic structure of the thallus:
- Homeomeric;
- heteromeric.
On a cross section of a lichen homeomeric type there is an upper and lower bark, which consists of one layer of fungal cells. The entire inner part is filled with loosely arranged fungal filaments, between which algae cells are located without any order.
in lichen heteromeric type of algae cells are concentrated in one layer, which is called gonidial layer. Below it is the core, consisting of loosely arranged filaments of the fungus.
The outer layers of the lichen are dense layers of fungal filaments called cortical layers. With the help of fungal filaments extending from the lower cortical layer, the lichen is attached to the substrate on which it grows. In some species, the lower bark is absent and it is attached to the substrate by the threads of the core.
The algal component of the lichen consists of species belonging to the blue-green, green, yellow-green and brown divisions. Representatives of 28 genera of them enter into symbiosis with fungi.
Most of these algae may be free-living, but some are found only in lichens and have not yet been found in a free state in nature. Being in the thallus, algae change greatly in appearance, and also become more resistant to high temperatures, and can tolerate prolonged drying. When cultivated on artificial media (separate from fungi), they acquire a form characteristic of free-living forms.
The lichen thallus is diverse in shape, size, structure, painted in various colors. The color of the thallus is due to the presence of pigments in the shells of hyphae and fruiting bodies of lichens. There are five groups of pigments: green, blue, purple, red and brown. A prerequisite for the formation of pigments is light. The brighter the lighting in the places where lichens grow, the brighter they are colored.
The shape of the thallus can also be varied. According to the external structure of the thallus, lichens are divided into:
- scale;
- leafy;
- bushy.
At scale lichens the thallus has the appearance of a crust, tightly fused with the substrate. The thickness of the crusts is different - from a barely noticeable scale or powdery coating to 0.5 cm, the diameter - from a few millimeters to 20-30 cm. Scale species grow on the surface of soils, rocks, bark of trees and shrubs, and exposed decaying wood.
foliose lichens have the form of a leaf-shaped plate, horizontally located on the substrate (parmelia, wall goldfish). Usually the plates are rounded, 10-20 cm in diameter. A characteristic feature of leafy species is the unequal color and structure of the upper and lower surfaces of the thallus. In most of them, on the underside of the thallus, organs of attachment to the substrate are formed - rhizoids, consisting of hyphae collected in strands. They grow on the surface of the soil, among mosses. Leafy lichens are more highly organized forms compared to scale ones.
fruticose lichens have the form of an upright or hanging bush and are attached to the substrate in small areas of the lower part of the thallus (cladonia, Icelandic lichen). According to the level of organization, bushy species are the highest stage in the development of the thallus. Their thalli are of different sizes: from a few millimeters to 30-50 cm. Hanging thalli of fruticose lichens can reach 7-8m. An example is a lichen hanging in the form of a beard from the branches of larches and cedars in taiga forests (bearded lichen).
reproduction
Lichens reproduce mainly vegetatively. At the same time, pieces are separated from the thallus, carried by wind, water or animals, and in favorable conditions give new thalli.
In foliose and bushy lichens, for vegetative propagation in the surface or deeper layers, special vegetative formations are formed: soredia and isidia.
Soredia have the appearance of microscopic glomeruli, each of which contains one or more algae cells surrounded by fungal hyphae. Soredia are formed inside the thallus in the gonidial layer of leafy and fruticose lichens. Formed soredia are pushed out of the thallus, picked up and carried by the wind. Under favorable conditions, they germinate in new places and form thalli. About 30% of lichens reproduce by soredia.
Nutrition
The nutritional characteristics of lichens are associated with the complex structure of these organisms, consisting of two components that receive nutrients in different ways. Mushrooms are heterotrophs and algae are autotrophs.
The algae in the lichen provides it organic matter produced by photosynthesis. The lichen fungus receives high-energy products from the algae: ATP and NADP. The fungus, in turn, with the help of filamentous processes (hyphae) acts as a root system. So the lichen gets water and minerals that are adsorbed from the soil.
Also, lichens are able to absorb water from the environment with their whole body, during fogs and rains. To survive they need nitrogen compounds. If the algal component of the thallus is represented by green algae, then nitrogen comes from aqueous solutions. When blue-green algae act as a phycobiont, nitrogen fixation from atmospheric air is possible.
For the normal existence of lichens are necessary in sufficient quantities light and moisture. Insufficient illumination prevents their development, as photosynthetic processes slow down and lichens receive less nutrients.
Light pine forests have become the best place for their life. Although lichens are among the most drought-resistant species, they still need water. Only in a humid environment are respiratory and metabolic processes carried out.
The value of lichens in nature and human life
Lichens are very sensitive to harmful substances, therefore they do not grow in places with high dust and air pollution. So, they are used as indicators of pollution.
They take part in the cycle of substances in nature. Their photosynthetic part is capable of producing organic matter in places where other plants cannot survive. An important role of lichens in soil formation, they settle on a lifeless rocky surface and, after dying off, form humus. This creates favorable conditions for plant growth.
Forage lichens are an important link in the food chain. For example, deer, roe deer, moose feed on deer moss or reindeer moss. They serve as material for bird nests. Lichen manna or Aspicilia edible is used in cooking.
The perfume industry uses them to give durability to perfumes, and the textile industry uses them to dye fabrics. Species with antibacterial properties are also known, which are used in the manufacture of medicines to combat tuberculosis and furunculosis.
And cyanobacteria. The name of the organisms comes from the similarity of their appearance with some skin diseases, and is translated from Latin as "lichen".
Description of symbiotes
They are distributed throughout the earth and can grow equally well both in cold rocky terrain and in hot deserts. Their color can be of the most varied colors: red, yellow, white, blue, brown, black. The mechanism of lichen formation is not fully understood. But with accuracy we can say that their formation is influenced by sunlight. There are also leafy lichens. The thalli of the former are similar to a crust that adheres tightly to the substrate. They are small (up to 2-3 cm), merge with each other, grow on the surface of tree trunks, rocks, forming conglomerates with a diameter of tens of centimeters. Bushy - more developed organisms that grow vertically and can reach several meters in height. But in this article we will take a closer look at the second variety of organisms, the appearance and structure of foliose lichens, reminiscent of their trees.
What are the structural elements
Thallus or thallus is an integral part of unicellular or multicellular fungi, mosses and lichens. If compared with plants, then for them it is their young green branches. The thalli may be leaf-shaped or bushy.
Hypha is a filamentous formation resembling a web. It is multinucleated and multicellular. And it is intended to absorb nutrients, water and, like a web, can serve to catch other organisms (for example, in predatory mushrooms).
The substrate is the surface to which the object is attached. It is also a breeding ground for some plants and lichens.
foliose lichens
Their thallus is rounded, leaf-shaped and lamellar, sometimes consisting of one or more parts. And hyphae grow along the edges or along the radius of the circle. Leafy lichens have the form of a layered plate located on the substrate in a horizontal manner. The correctness of the shape of the thallus depends on the surface of the substrate. The smoother it is, the more rounded the lichen will look.
It is attached to the base with the help of a thick short leg located in the center of the thallus. The plate itself with a diameter of no more than 20-30 cm is quite dense and leathery. Its shade can vary from dark green or gray to brown and black. They grow very slowly, but foliose lichens are somewhat faster than other varieties. In addition, they are long-lived. Some thalli are over a thousand years old. There is a direct relationship between the immobility of the substrate and the life span of the lichen.
Structure
Leafy lichens have a two-level thallus due to their dorso-vertral structure. That is, they have an upper and lower surface. The upper part is rough or even, sometimes covered with outgrowths, tubercles and cilia, warthogs. On the bottom there are organs with which the lichen is attached to the substrate. In structure, it can also be smooth or uneven. Both parts differ not only in shape, but also in color intensity.
Under the microscope, four main anatomical layers are clearly visible:
- upper cow;
- algal;
- core;
- lower cow.
Leafy lichens are loosely attached to the surface of the substrate and are easily separated from it. But between the thallus and the base, it is formed. It nourishes the constituent parts of the lichen with oxygen, carrying out gas exchange, and contributes to the accumulation and preservation of moisture. The hyphae consists of special attachment organelles - rhizoids.
The thallus can be from one plate, then it is monophilic, or from several layers and is called polyphilic. The latter do not have a leg, their base is firmly attached to the surface, so they hold onto the substrate more firmly. They are not afraid of winds, hurricanes and other bad weather. The thallus can be dissected into lobes, cut along the edges, divided into lobes. Sometimes the appearance of a lichen resembles an intricately woven lace fabric.
Spreading
Leafy lichens grow in areas with high rainfall. They are easy to find on all continents, including even cold Antarctica. They can be placed on bare stones and rocks, on the trunks of shrubs and trees, mossy stumps, on old buildings. They grow along roads, in swamps, edges and dry meadows. Basically, their geographical location is precisely due to the choice of substrate. With the deterioration of the environment, lichens often change color closer to dark and gray. Ground organisms grow especially luxuriantly, covering vast areas of the earth. These include (Kladonia forest).
Types of foliose lichens
More than 25 thousand species of lichens are distributed throughout the globe. If you divide organisms according to the substrate to which they prefer to attach, then there are:
- Epigeic - located on soil or sand (for example, Parmelia brown, Hypohymnia Nephrom, Solorina).
- Epilithic - attached to stones, rocks (Gyrofora, Collem, Xanthoria, Cetraria).
- Epiphytic - grow on trees and bushes, mainly on leaves and trunks (Parmelia, Fiscia, Cetraria, Lobaria, Candelaria).
- Epixial - located on dead trees, stumps without bark, walls of old buildings (Hypohymnia, Parmeliopsis, Xanthoria).
It must be remembered that the same genus may include species with both foliose thalli and fruticose, or their intermediate forms.
Lichen Parmelia
In its internal structure, it is very similar to green algae. Its surface can be yellow, brown with green, black and white patches. The genus Parmelia is a leafy lichen, which has about 90 species only in Russia, has a thallus cut into large pieces. Its blades can be both narrow and wider. It grows equally well on tree trunks and on stones, and adapts to the polluted urban climate. The form of this living organism is so diverse that it confirms the fact that it is not always advisable to classify lichens only in appearance. During World War II, parmelia powder was used to stop bleeding from wounds. It was also added to flour to protect it from pests and increase shelf life.
Leafy lichens, whose names are determined not only by the structure and shape, but also by the habitat halo, the type of substrate, are very diverse. Many of them are used in the food industry. They are fed large and. Recently, the powder of them is widely used as food additives that make up pharmaceutical preparations. Cetraria, for example, is used in the manufacture of anti-diarrhea remedies, to stimulate the immune system, to normalize the organs of the digestive tract, and it is also part of many antiviral drugs.
Lesson topic: Lichens. General characteristics and significance.
Lesson type: learning new material
Goals: to study the structure of lichens as symbiotic organisms.
Lesson objectives.
Educational : to form knowledge about the features of the structure and life of lichens as symbiotic organisms; show the adaptability of lichens to a variety of habitat conditions; their role in nature and in human life.
Educational : generate cognitive interest in this topic; develop the ability to compare, analyze, conduct simple laboratory experiments.
Educational : to cultivate love for the nature of the native land and the need to preserve the surrounding world.
Equipment : multimedia projector, presentation "Lichens", herbarium "Types of lichens", lichens, Petri dishes, glasses of water.
1. Organizational
Greetings.
Identification of absentees.
Checking students' readiness for the lesson.
2. Study of new material.
Listen to one legend.
The Bible tells of a people who wandered through the desert for many days, knee-deep in the sand. All supplies taken with them were eaten. Many fell from exhaustion and exhaustion on the hot sand. In the morning, when the sun began to heat up the sand, the wind suddenly rose. And they saw gray lumps rolling along the sand, driven by the wind. A strong gust of wind lifted them up, and it seemed that they were falling from the sky. "Manna, manna! Manna is falling from the sky!” Everyone who still could rushed to collect this "manna". They eagerly ate dry gray lumps, cooked porridge from them and baked cakes.
What was this manna really?
In today's lesson, we will get acquainted with amazing organisms - lichens. Lichens (according toKomi: swarm, nitsh) is a large, peculiar and relatively little studied group of living organisms. According to various estimates, there are from 13,500 to 17,000 species in the world. About 1000 species of lichens have been identified in the Komi Republic.Studying lichenslichenology . This science arose in 1803, when the Swedish botanist Eric Acharius singled out lichens as a separate group and described 906 species known at that time.
Lichens are one of the longest living organisms on the planet. They can livefrom several hundred to 4500 years. At the same time, lichens grow very slowly, growing from a few tenths of a millimeter to several centimeters per year.
The topic of today's lesson. "Lichens. General characteristics and meaning »
What do you think we should learn about lichens in the lesson?
1. Where are lichens found? (Spreading).
2. What is their structure?
3. Nutrition.
4. How do lichens reproduce?
5. The value of lichens in nature and human life.
Before proceeding to the study of lichens, let's recall the common signs of fungi and algae.
Task 1. Select the features characteristic of fungi and algae.
They feed on ready-made organic substances, heterotrophs.
They themselves form organic substances, autotrophs.
Relate to plants.
They are neither plants nor animals, they have similarities with them.
Consists of mushroom
It reproduces vegetatively (by mycelium), sexually and asexually (by spores).
Has chlorophyll.
Reproduces sexually and asexually
(Mushrooms - 1, 4, 5.6; algae - 2, 3, 7, 8).
1. Lichens grow on trees. In dry pine forests (pine forests), lichens form a carpet of branched whitish or pinkish "bushes" on the ground. In dry weather, they crunch underfoot.
In the tundra in the north of our Komi Republic, reindeer moss, or "reindeer moss", is very common. This is also not moss, but lichen.
Lichens in appearance are divided into three groups: fruticose, leafy, scale. Open the textbook, p. 206 and fill in the table.
Lichen groups
Name
Appearance
Where do they settle?
bushy
Reindeer moss
Bush
Soil, tree branches or rocks
Scale
Archil
"Crust", "scale"
Stones, rocks
foliose
Xanthoria wall
Records
Stones, soil, tree bark
2. Consider fig. 126 "Internal structure of a lichen". Guess the riddle:
I looked at the bark on the branch.
Through chiseled glass:
There in the cells of the white grid
Fish sleep green.
Q. What do you think, what organisms are we talking about? (about fungi and algae).
Conclusion: The body (thallus) consists of two organisms: a fungus and an algae.
3. And now let's talk about nutrition. How does a lichen eat?
Algae create organic matter through photosynthesis. The fungus absorbs water and mineral salts with its hyphae.(Take a piece of lichen and place it in water, pay attention to how quickly the hyphae of the fungus absorb water)
Guess the riddle:
Klim conspired with Pakhom
Live together, in a common home:
Klim prepares salt, water,
And Pakhom - grain, flour.
Match the names of groups of organisms and their features.
Groups of organisms
Peculiarities
Symbionts
Saprotrophs
Predators
A) Catch their prey, kill and eat
B) Live with other organisms and often bring them tangible benefits.
C) They live inside or on another organism, take shelter and feed on its tissues
D) Extract nutrients from dead and decaying organic material.
(1 - B; 2 - D; 3 - C; 4 - A)
I think that now we can define "What is a lichen?". (The definition is formulated by the students. ) Lichens are single organisms consisting of a fungus and an algae connected by a symbiosis (symbiotic relationship), a symbiosis of a fungus and an algae.
Question: What kingdom do lichens belong to? (to bacteria, plants, fungi, animals)
4. Reproduction.
Spores or pieces of thallus. (Break the lichen into small pieces - this is vegetative propagation).
Having become single organisms, they developed their own methods of reproduction, for example, with the smallest balls, consisting of one or two algae cells, surrounded by fungal hyphae. These "balls" are formed inside the thallus in large numbers, under the pressure of their overgrown mass, the body of the lichen is torn and the "balls" are carried by the wind.
Sometimes special outgrowths containing both components of the lichen are formed on the surface of the thallus. They flake off and are carried by wind or water. Lichens can also multiply by simply breaking off pieces of thallus.
In addition, the fungus and algae that make up the lichen retain their own methods of reproduction - spores and vegetatively.
5.Value.
1) Probably, many of you have seen shaggy gray "beards" hanging from branches in a dark spruce forest. This is a bearded lichen. Especially a lot of it in the forests away from industrial centers. What does this fact say? Lichens "do not like" dirty air. Therefore, by the number of lichens, one can judge the purity of the air. Lichens are indicators.
2) Lichens are very unpretentious, they grow in the most barren places and even on bare rocks, in the harshest conditions of the Arctic or high mountains, on the poorest soils of the tundra, peat bogs, on sand, glass, iron, bricks, tiles, bones, resin, faience, porcelain, leather, cardboard, linoleum, charcoal, felt, linen and silk fabrics, and even on old cannons. Settling on stones, they release special substances - lichen acids, which dissolve and destroy the stone. After the death of lichens, other plants can already settle here. And lichens, because they appear first in barren places, are called pioneers of vegetation - pioneers.
3) Included in the diet of reindeer and many other animals.
4) Most lichens lead an attached lifestyle. But among them there are also "nomadic" species. For example, edible aspicilia in the form of spherical lumps is carried by the wind over long distances, and, settling in new places, forms deposits. The biblical legend of manna from heaven is associated with this lichen.
During the Soviet-Finnish war of 1939-1940. in the rear of the FinnishThe army landed a large landing force, whose task was to sabotage behind enemy lines, destroy communications, and reconnaissance. It was assumed that the landing force would be able to easily provide itself with food by hunting animals, catching fish and birds. However, the organizers of this operation did not take into accountthat the northern nature would not be able to withstand such a load, and a significant part of the large (over a thousand people) landing force died of starvation.
During the expedition of the English polar explorer JohnFranklin, its participants suffered great hardships due to lack offood. They ate the leather of belts and boots, they also tasted lichens. However, they did not know how to get rid of bitter lichen acids andtherefore, some members of the expedition were poisoned. Later they noticed that the Indians mostly eat Mullenberg's Umbilicaria.(Umbilicaria mullenbergii) and began to collect this type of lichen.
There are cases when pilots who crashed in the tundrawere dying of hunger, while they practically went "for food":the lichens that form the basis of the reindeer moss are quite edible. For thisit is necessary to thoroughly soak the collected lichen thalli ina solution of soda or potash (potassium carbonate and sodium are contained inash), preferably 2-3 days, rinse thoroughly, periodically changing the waterand cook until a brew is formed, slightly resemblingToisel. Such jelly is not very nutritious, but for lack of other foodcan support strength and prevent starvation.
5) Scale lichens diplochistes, Paschal lecidia and fiscia helped to determine the age of the famous statues on about. Easter. Comparing photographs of these sculptures taken at the beginning of the century with modern ones, scientists noticed that the curtains - lichen "plaques" - have grown a little. Scientists have calculated the average growth of lichen per year. Assuming that lichens appeared on the stones almost immediately after the creation of the sculptures, scientists calculated the age of the sculptures - about 430 million years, much less than expected.
6) Lichens are used to obtain medicines ( for example, Icelandic cetraria is a component of cough medicines, and weed contains the antibiotic usnic acid, which is used for skin diseases).
7) Everia plum, known asonglobalmarketundername- « oakmoss». Fromthislichenreceive resinoidconcentratedalcoholicextract, havingkind of thickliquidsdarkcolors. Resinoid- aromaticsubstance, hisuseonperfume factoriesVqualityaromaticstartForsomevarietiesspirits. ExceptTogo, Hehas the propertyretainersmell, AndperfumersVsomecasesusehisForadditionsresiliencespirits. ResinoidincludedVcompoundthe wholerowspiritsAndcolognes. So, Vourcountryonhisbasissuchperfume, How« Bakhchisaraifountain», « Crystal», « Carmen», « Gift», « Gull», « East» Andothers., AAlsocolognes« Chypre», « New» Andsomeother. ResinoiduseAndVotherscosmetic products- Vcreams, powders, soaps, dry spirits.
8) So times deep antiquities lichens served raw materials For receiving dyes. These dyes used For coloring wool And silks. Basic color dyes, received from lichen substances, dark- blue. But additive acetic acids, alum And T. d. gives purple, red And yellow tones. Significantly, What paints from lichens possess especially warm And deep tones, Although they and unstable By relation To light. IN the present time paints receive main way synthetically, But before now since V Scotland V textile industry